The purpose of our project is to study the relationships of erythrocyte metabolism with the plastic properties of the membrane. The eventual aim is to use this information in the understanding of the pathophysiology of hemolytic disease, the red blood cell storage lesion and the biological properties of the membrane in general. To date we have shown that the energy requirements for endocytosis expressed in the form of ATP differ in the three classes of drugs studied: Primaquine, Vinblastine and Chlorpromazine. Primaquine has the most definitive requirements for ATP whereas Chlorpromazine appears to be able to produce endocytosis even when ATP stores are reduced to 20% of control. Therefore the mechanism of drug induced endocytosis may not be the same for these three classes of drugs. Addition of small amounts of Ca ions to the interior of the intact erythrocyte results in enhanced drug induced endocytosis as predicted from our studies with ghost endocytosis. Microfibrils seem relatively unimportant in endocytosis in intact erythrocytes since cytochalasin B does not alter the phenomenon. In sickle cell anemia, the presence of small amounts of deoxy sickle hemoglobin interferes with drugs induced endocytosis because gassing sickle erythrocytes with carbon monoxide results in a 30-50% improvement in drug induced endocytosis, whereas CO produces no effect in normal red cells. Storage of RBC for 6 weeks produces a membrane defect not correctable by rejuvenating intra-erythrocyte ATP levels. This membrane defect is best expressed in markedly impaired primaquine induced endocytosis, thus indicating a membrane storage lesion. Our current studies are designed to explore the role of spectrin and related polypeptides in endocytosis in resealed ghosts. We also plan to study erythrocyte membrane polypeptides using antibodies raised to specific fractions bound to affinity columns. BIBLIOGRAPHIC REFERENCES: Schrier, S.L. Human Erythrocyte Membrane Enzymes: Current Statistical and Clinical Correlates. Blood, 1977, in press. Avoy, D., Ellison, S., Nolan, N., Cox, R., Franco, J., Harbury, C.B., Schrier, S.L., and Pool, J.G. The effect of delayed refrigeration on red cells and platelet concentrate and cryoprecipitated AHF. Transfusion, 1977, in press.